A water repellent sand layer that is made of water repellent sand and serves as a water shield layer is provided to be slanted between upper and lower soil layers, a water conveying belt portion is provided to include at least one or both of gravel and a culvert that are provided between the water repellent sand layer and the upper soil layer, and a water shield wall is provided at a slant downstream side. Water falling and permeating from a ground surface into the soil layer is blocked by the water repellent sand layer, flows downward in the water conveying belt portion located above the water repellent sand layer to the slant downstream side, and is blocked by the water shield wall at the slant downstream side, so that the collected water is recovered from a drain hole in the culvert that penetrates the water shield wall.
